Modal decomposition of magnetic maps: the case of Cape Roberts aeromagnetic survey, Antarctica

Abstract

This paper proposes a digital enhancement tool for magnetic anomaly maps. The magnetic anomaly map is decomposed<br />by means of Eigenvalue Decomposition into a number of orthogonal bases. The dataset is then filtered<br />accordingly to a specific variance pattern. The dataset is decomposed and the eigenvalues population is inspected<br />so that the variance is evaluated yielding the definition of two thresholds. Subsequently, the dataset is<br />reconstructed into three subsets which hold different features respectively. The proposed filtering procedure is<br />first tested with a synthetic signal and then applied to the data of Cape Roberts (Antarctica) aeromagnetic survey,<br />flown over an off-shore rift basin. The proposed method appears to be efficient in noise removal and acts as<br />a digital enhancement tool which provides TMI anomaly maps revealing hidden lineaments, otherwise not visible.<br />The methodology effectiveness as a hidden lineaments detection tool has been checked against independent<br />data.

Keywords

• Magnetic mapping – Digital Enhancement – Eigenvalues – HRAM – Antarctic Magnetic Surveys